Hi,
Create a service with input infotable (this is coming from SelectedRows of the list). In this service you can add info in a datatable already created, with service AddorUpdateDataTableEntry. Unfortunately, there is no service that creates datatable that I am aware of.
Same can be achieved if you want to insert data in a Database (you need a Database Thing that is connecting to the database), providing SelectedRows as input to a service, iterate through infotable and insert field/value in database.
Make sure ValueField property of List widget has the correct value (it should be the name of the field in your case).
Hope it helps,
Raluca Edu